1. Field of the Invention
The present invention relates to a wireless device including a plurality of wireless or radio communication portions using the same frequency band.
2. Description of Related Art
Recent prior art networks that connect wireless devices are designed according to standards of IEEE 802.11 and Bluethooth (registered trademark).
The wireless devices such as a cordless telephone set operate in the same frequency band of 2.4 GHz referred to as an ISM (Industry Science Medical) band, so that wave interferences may take place where the same frequency band is concurrently used by the wireless devices located in a narrow area, giving rise to unsatisfactory communication results.
According to prior art solutions for minimizing the wave interferences caused by the use of the same frequency band by a plurality of wireless devices in a narrow area, a bit error rate or an electric field intensity is measured for each of frequency channels prior to communication, so that the use of frequency channels that involve considerable wave interferences is inhibited to minimize the wave interferences. Examples of such prior art solutions are disclosed in JP-2002-198867A and JP-2002-198868A.
Where a plurality of time slots for measuring the electric field intensity are provided for the respective frequency channels, according to the above-indicated prior art solutions, however, signal transmission may be delayed, resulting in sound interruption or delayed sound transmission or reception in wireless or radio communication by a digital cordless telephone set, for example, which requires real-time communication. Accordingly, the prior art solutions are not satisfactory for reliable and stable communication by the digital cordless telephone set.